Periodic table atomic number9/12/2023 ![]() ![]() there is really no reason to convert to grams first and then back out to pounds later. How? Well IF the problem is stated in say pounds, and then wants the answer in pounds. Quite the rigorous path for "all" problems. And finally, convert those grams into any other unit needed that might be asked for. Then (if need be) convert your answer in moles into grams. Then, convert those grams in to moles and work the problem in moles only. In general, to work all types of stoichiometry problems, we say to convert all masses to grams first. Those atomic weights are the number of grams you will need of that element in order to have exactly 1 mole of that element. Counting by number is the molar amount, while measuring by mass is the. This helps tremendously when having to convert from moles to mass as we often do in chemistry. ![]() Because of that old definition, we were able to say that all those atomic weights are in grams per mole of substance or abbreviated g/mol. So why DO we seem to concentrate on the "gram" as our go to guy on the periodic table for atomic weights and ultimately for molar masses and molecular weights? Well the key here is the way we historically defined the mole. All chemical ratios work just as well with masses as they do with our oh so familiar moles. You can work chemistry mass problems in any mass you want and it will still work because the masses are relative to each other. Not to mention the myriad of masses represented by all the metric prefixes to prepend to "gram". short tons, long tons, drams, grains, or stones. You could think in pounds, or kilograms, or ounces, or even tons, or heaven forbid. Relative masses means that they are all corrected relative to each other. BUT it would be much much better for you to realize that those could be ANY unit of weight/mass you choose and the whole table would still be correct. "Well, I know the weights are in grams because that is how I learned it in high school". Notice how the atomic weights have no units after them. Hey you! LOOK again at any periodic table - including the one above. The diagram below illustrates the parts and their definitions. You need to make sure that you know what each of these parts is and what it represents. You want a lot more periodic tables to chose from? *Note: If you click on the table, you'll launch it into its own window/page on your browser. These three pieces of data are the elemental symbol, the atomic number (typically given the symbol, Z, and the atomic weight. In it's simplest form (shown below), each entry only has three pieces of information that you will need to know. ![]() Therefore, there are various non-equivalent definitions of atomic radius.The periodic table can often be presented with an abundance of data about each and every element listed. However, this assumes the atom to exhibit a spherical shape, which is only obeyed for atoms in vacuum or free space. The atomic radius of a chemical element is a measure of the distance out to which the electron cloud extends from the nucleus. ![]() It must be noted, atoms lack a well-defined outer boundary. The atomic radius of Nihonium atom is 175pm (covalent radius). Note that, each element may contain more isotopes, therefore this resulting atomic mass is calculated from naturally-occuring isotopes and their abundance. The atomic mass is carried by the atomic nucleus, which occupies only about 10 -12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. The atomic mass or relative isotopic mass refers to the mass of a single particle, and therefore is tied to a certain specific isotope of an element. Mass numbers of typical isotopes of Nihonium are 278,282-287. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.įor stable elements, there is usually a variety of stable isotopes. Neutron number plus atomic number equals atomic mass number: N+Z=A. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10 -19 coulombs. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. Nihonium is a chemical element with atomic number 113 which means there are 113 protons in its nucleus. Atomic Number – Protons, Electrons and Neutrons in Nihonium ![]()
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